1. Technical Field
The present invention relates to a substrate for an electro-optical device used in an electro-optical device such as a liquid crystal device, an electro-optical device including the substrate for the electro-optical device, and an electro-optical apparatus including the electro-optical device, such as a liquid crystal projector.
2. Related Art
A liquid crystal device which is an example of an electro-optical device is, for example, used as an optical modulation unit (a light valve) of a projection type display device as well as a direct view type display. In particular, in the projection type display device, since strong light from a light source is input to a liquid crystal light valve, a light-shielding film is mounted in the liquid crystal light valve as a light-shielding section for blocking incident light such that a thin-film transistor (TFT) in the liquid crystal light valve does not cause the increase of leak current or malfunction by the light. With respect to the light-shielding section or the light-shielding film, for example, JP-A-2004-4722 discloses a technology of shielding light by a scanning line functioning as a gate electrode in a channel region of a TFT. According to Japanese Patent No. 3731447, light which reaches a channel region of a TFT is reduced by providing a plurality of light-shielding films formed on the channel region and a layer for absorbing inner reflection light. JP-A-2003-262888 discloses a technology of significantly reducing incident light input to a channel region of a TFT while narrowing scanning lines and ensuring a suitable operation of the TFT.
Meanwhile, in such an electro-optical device, retention capacitors for holding the charges of pixel electrodes for a predetermined time period by temporarily holding image signals supplied to the pixel electrodes are provided on a region in which a light-shielding film is formed on a substrate, that is, a region of the substrate which does not transmit light. Such retention capacitors may shield TFTs from light by using electrodes, which are the component of the retention capacitors, as a light-shielding film.
However, for example, when light is irradiated to a junction region, such as a lightly doped drain (LDD) region, formed between a channel region and source and drain regions, light leak current occurs in the junction region. In order to solve such a problem, a light-shielding section may be provided on the junction regions of the both sides of the channel region. However, narrowing of an opening region which substantially transmits light in a pixel is not preferable in view of display performance. Meanwhile, the present inventor observes that, when light is irradiated to a junction region formed between the source and drain regions and the channel region connected to the pixel electrode, light leak current is easy to occur in the TFT, compared with a case where light is irradiated to a junction region formed between the source and drain regions and the channel region connected to a data line.